Method of making a light emitting device and light emitting device made thereof

ABSTRACT

A light-emitting device, includes: a semiconductor stack, including a top surface, wherein the top surface includes a first region and a second region which are coplanar; a current barrier layer formed on the first region, wherein the current barrier layer includes an insulating material; and a transparent conductive layer formed on the current barrier layer and the second region; and a first electrode formed on the transparent conductive layer; wherein the current barrier layer includes: an electrode region at a position corresponding to the first electrode, having a shape substantially the same as the first electrode; and a plurality of extension regions extending from the electrode region and not covered by the first electrode.

RELATED APPLICATION

This application a continuation application of U.S. patent applicationSer. No. 15/703,649, entitled “METHOD OF MAKING A LIGHT EMITTING DEVICEHAVING A PATTERNED PROTECTIVE LAYER”, filed on Sep. 13, 2017, which is acontinuation application of U.S. patent application Ser. No. 15/240,264,entitled “LIGHT EMITTING DEVICE”, filed on Aug. 18, 2016, now U.S. Pat.No. 9,786,815, which is a continuation application of U.S. patentapplication Ser. No. 14/098,643, entitled “LIGHT EMITTING DEVICE”, filedon Dec. 6, 2013, now U.S. Pat. No. 9,425,362, which claims priority frompreviously filed Taiwan Patent Application No. 101146337 filed on Dec.7, 2012, entitled as “METHOD OF MAKING A LIGHT EMITTING DEVICE AND LIGHTEMITTING DEVICE MADE THEREOF”, and the entire contents of which arehereby incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates to a method of making a light-emittingdevice and in particular to a method of etching a protective layer.

Description of the Related Art

The light-emitting diodes (LEDs) of the solid-state lighting elementshave the characteristics of the low power consumption, low heatgeneration, long operational life, shockproof, small volume, quickresponse and good opto-electrical property like light emission with astable wavelength so the LEDs have been widely used in householdappliances, indicator light of instruments, and opto-electricalproducts, etc.

Generally speaking, the method of making a light-emitting diodecomprises many lithography processes and each of the processes comprisescomplicated steps. How to reduce the steps of processes and decrease thecost is an important issue.

Besides, light-emitting diodes can be further combined with a sub-mountto form a light emitting device, such as a bulb. The light-emittingdevice comprises a sub-mount with circuit; a solder on the sub-mountfixing the light-emitting diode on the sub-mount and electricallyconnecting the base of the light-emitting diode and the circuit of thesub-mount; and an electrical connection structure electricallyconnecting the electrode pad of the light-emitting diode and the circuitof the sub-mount; wherein the above sub-mount can be a lead frame or alarge size mounting substrate for designing circuit of thelight-emitting device and improving its heat dissipation.

SUMMARY OF THE DISCLOSURE

A light-emitting device, includes: a semiconductor stack, including atop surface, wherein the top surface includes a first region and asecond region which are coplanar; a current barrier layer formed on thefirst region, wherein the current barrier layer includes an insulatingmaterial; and a transparent conductive layer formed on the currentbarrier layer and the second region; and a first electrode formed on thetransparent conductive layer; wherein the current barrier layerincludes: an electrode region at a position corresponding to the firstelectrode, having a shape substantially the same as the first electrode;and a plurality of extension regions extending from the electrode regionand not covered by the first electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1H show a cross-sectional view of a method of manufacturing alight-emitting device in accordance with an embodiment of the presentdisclosure.

FIG. 2A shows a light-emitting device in accordance with an embodimentaccording to the manufacturing method of the present disclosure.

FIG. 2B shows a partial enlarged drawing of FIG. 2A.

FIGS. 3A-3C show top views of light-emitting devices in accordance withembodiments of the present disclosure.

FIG. 4 shows an exploded drawing of a bulb in accordance with anembodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The drawings illustrate the embodiments of the application and, togetherwith the description, serve to illustrate the principles of theapplication. The same name or the same reference number given orappeared in different paragraphs or figures along the specificationshould has the same or equivalent meanings while it is once definedanywhere of the disclosure. The thickness or the shape of an element inthe specification can be expanded or narrowed. It is noted that theelements not drawn or described in the figure can be included in thepresent application by the skilled person in the art.

FIGS. 1A-1G show figures of a method of manufacturing a light-emittingdevice 100 in accordance with an embodiment of the present disclosure.

As shown in FIG. 1A, a substrate 10 a is provided and a light-emittingstructure 11 is formed on the substrate 10 a. In this embodiment, thesubstrate 10 a is a sapphire wafer substrate. The light-emittingstructure 11 sequentially comprises a first type semiconductor layer111, an active layer 112, and a second semiconductor layer 113 on thesubstrate. The first type semiconductor layer 111 and the secondsemiconductor layer 122 can be a cladding layer or a confinement layerseparately provides an electron and a hole to be combined with eachother in the active layer 112 and emits a light. As shown in FIG. 1B,etching the active layer 112 and the second type semiconductor layer 113to from a plurality of light-emitting structures 1000. A plurality ofthe light-emitting structures 1000 are spaced arranged on the substrate10 a and expose a part of the first semiconductor layer 111. Besides,the light-emitting device 100 is a horizontal type structure but canalso be a vertical type structure or other type structure. As shown inFIG. 1C, a protection layer 12 is formed to cover the first typesemiconductor layer 111, the active layer 112, the second typesemiconductor layer 113 and the substrate 10 a. The protective layer 12has a first thickness t₁ and is configured to protect the light-emittingstructure 11 during the following etching process. In this embodiment,the first thickness t₁ is between 3300-10000 Å. As shown in FIG. 1D, alaser is applied to cut the substrate 10 to form a trench 16 in thesubstrate 10, wherein the cross section of the trench 16 is a triangle.It is noted that byproducts are generated when using a laser to cut thesubstrate 10, and an etching step is applied to remove the byproducts.However, the protective layer 12 is also etched while etching thebyproducts. Therefore, as shown in FIG. 1E, the protective layer 120 hasa second thickness t₂ between 3000-9700 Å after etching the byproductsand the second thickness t₂ is less than the first thickness t₁. Thedifference between the first thickness t₁ and the second thickness t₂ islarger than 300 Å. In this embodiment, the method of etching thebyproducts and etching the protective layer 12 at the same timecomprises using an acidic solution to etch the byproducts and theprotective layer 12. The acidic solution comprises a mixture solution ofa phosphoric acid solution and a sulfuric acid solution, wherein a ratiobetween the sulfuric acid and the phosphoric acid is about 3:1. Inanother embodiment, the acidic solution is a phosphoric acid solution.As shown in FIG. 1F, the protective layer 120 is patterned to be apatterned protective layer 121. In this embodiment, the patternedprotective layer 121 is also configured to be a current barrier layer121. As shown in FIG. 1G, a transparent conductive layer 13 is formed onthe barrier layer 121 and the second semiconductor layer 113. As shownin FIG. 1H, a first electrode 14 is formed on the transparent conductivelayer 13 at the position corresponding to the barrier layer 121 and asecond electrode 15 is formed on the first type semiconductor layer 111.The protective layer 121 or the barrier layer 121 is an insulatingmaterial and has a transmittance larger than 90%. Besides, the barrierlayer 121 has a resistance larger than 10¹⁴ Ω-cm. The barrier layer 121comprises silicon oxide (SiO₂), silicon nitride (SiN_(x)) or titaniumdioxide (TiO₂). Then, splitting the light-emitting structure 1000 alongthe trench 16 to form a plurality of light-emitting devices 100.

FIG. 2A shows a light-emitting device 100 based on the method describedin FIGS. 1A-1H. FIG. 2B shows a partial enlarged drawing of FIG. 2A. Thelight-emitting structure 11 is formed on the substrate 10 b. Thelight-emitting structure 11 sequentially comprises a first typesemiconductor layer 111, an active layer 112, and a second typesemiconductor layer 113. The second type semiconductor layer 113comprises a first region 1131 and a second region 1132. A barrier layer121 is formed on the first region 1131 and has a lower surface 1211 anda side wall 1212 which is inclined against the lower surface 1211 and anangle (Θ) between the sidewall and the bottom surface is between10°-70°. A transparent conductive layer 13 is formed on the side wall1212 of the barrier layer 121 and has a third thickness (t₃); thetransparent conductive layer 13 is also formed on the second region 1132of the second semiconductor layer 113 and has a fourth thickness (t₄).Since the angle (Θ) between the sidewall 1212 and the lower surface 121is less than 70°, the transparent conductive layer 13 can cover the sidewall 1212 of the barrier layer 121 and the second region 1132 of thesecond semiconductor layer 113 uniformly. In this embodiment, adifference (t₃−t₄) between the thickness of the transparent conductivelayer 13 formed on the sidewall 1212 of the barrier layer 121 and thethickness of the transparent conductive layer 13 formed on the secondregion 1132 of the second semiconductor layer 113 and the thickness (t₃)of the transparent conductive layer 13 formed on the side wall 1212 ofthe barrier layer 121 forms a ratio ((t₃−t₄)/t₃) less than 10%. Besides,since a trench 16 of a triangular shape (referring to FIG. 1D) is formedin the substrate 10 a when applying a laser, an inclined sidewall 101 ofthe substrate 10 b is formed while splitting the light-emittingstructures 1000 to form a light-emitting device 100. The inclinedsidewall 101 is inclined against an upper surface 102 of the substrate10 b and an angle between the inclined sidewall 101 and the uppersurface 102 of the upper surface 102 is larger than 90°. Moreover, anacidic solution is used to remove the byproducts generated by lasercutting after the inclined sidewall 101 is cut by laser so that theinclined sidewall 101 has a rough surface.

FIGS. 3A-3C show top views of light-emitting devices 100, 100′ and 100″.The light-emitting device 100, 100′ or 100″ has a rectangular shape andhas a first side 104, a second side 105, a third side 106, and a fourthside 107. As shown in FIG. 3A, the light-emitting device 100 has a firstelectrode 14 near the first side 104 and the first electrode 14 isformed at the position on the transparent conductive layer 13 opposingto the barrier layer 121. In this embodiment, the first electrode 14 hasa shape substantially the same as that of the barrier layer 121. Thefirst electrode 14 comprises a first electrode pad 141 and a pluralityof first extended electrodes 142 extending from the first electrode pad141. The area of the barrier layer 121 is larger than the area of theelectrode pad 141 and the extended electrode 142. The light-emittingdevice 100 further comprises a second electrode 15 near the second side105 opposing to the first side 104. The second electrode 15 comprises asecond electrode pad 151 and a second extended electrode 152 extendingto the first side 104 while a first extended electrode 142 extends fromthe first electrode pad 141 to the second electrode pad 151 (in adirection toward the second side 105). Besides, the first electrode pad141 can also be placed at a corner near the first side 104 and the thirdside 106, the second electrode pad 151 can also be placed at a cornernear the second side 105 and the fourth side 107, and the secondextended electrode 152 extends toward the first electrode pad 141. Inanother embodiment, as shown in FIG. 3B, the light-emitting device 100′comprises a first electrode 14′ and a second electrode 15′. The firstelectrode 14′ comprises a first electrode pad 141′ and a first extendedelectrode 142′. The second electrode 15′ comprises a second electrodepad 151′. The first extended electrode 142′ extends in a direction fromthe first electrode pad 141′ to the second electrode pad 151′. Besides,a barrier layer 121 comprises an electrode region 1215, a plurality offirst extension regions 1213, and a plurality of second extensionregions 1214. The electrode region 1215 of the barrier layer 121 isformed on the region corresponding to the region of the first electrode14′ and has a shape substantially the same as the first electrode 14′and an area larger than that of the first electrode 14′. The firstextension region 1213 extends from the electrode region 1215 (the firstelectrode pad 141′ and the first extend electrode 142′) to the side wall(the third side 106 and the fourth side 107). In this embodiment, foursecond extension regions 1214 extend forward (in a direction to thefirst side 104) and backward (in a direction to the second side 105)form the electrode region 1215 (the first electrode pad 141′ and thefirst extend electrode 142′). The first electrode 14′ is not formed onthe first extension region 1213 and the second extension region 1214.

As shown in FIG. 3C, in another embodiment, the light-emitting device100″ comprises a first electrode 14″ and a second electrode 15″. Thefirst electrode 14″ comprises a first electrode pad 141″ and a firstextended electrode 142″. The second electrode 15″ comprises a secondelectrode pad 151″. The first extended electrode 142″ extends in adirection from the first electrode pad 141″ to the second electrode pad151″. Besides, a barrier layer 121 comprises an electrode region 1215′and a plurality of extension regions 1213′. The electrode region 1215′of the barrier layer 121 is formed on the region corresponding to thatof the first electrode 14″ and has a shape substantially the same as thefirst electrode 14″ and an area larger than that of the first electrode14″. A plurality of extension regions 1213′ extends from the electroderegion 1215′ (the first electrode pad 141″ and the first extendelectrode 142″) to four sides (104,105,106, and 107) at an angle of 45°.The first electrode 14″ is not formed on the extension region 1213′.

The first type semiconductor layer can be an n-type semiconductor andthe second type semiconductor layer can be a p-type semiconductor. Thefirst type semiconductor layer and the second semiconductor layercomprise AlGaAs, AlGaInP, AlInP, InGaP, AlInGaN, InGaN, AlGaN and GaN.Optionally, the first type semiconductor layer can be a p-typesemiconductor layer and the second type semiconductor layer can be ann-type semiconductor layer. The active layer comprises AlGaAs, AlGaInP,InGaP, AlInP, AlInGaN, InGaN, AlGaN and GaN. The active layer can be asingle heterostructure (SH), a double-side double heterostructure (DDH)or a multi-quantum well (MQW) structure. The substrate comprises GaAs,GaP, Ge, sapphire, glass, diamond, SiC, Si, GaN, and ZnO or othersubstitution material.

FIG. 4 shows an exploded drawing of a bulb 30 in accordance with anembodiment of the present disclosure. The bulb 30 comprises a cover 21,a lens 22, a light emitting module 24, a substrate 25, aheat-dissipation element 26, a connection element 27, and a circuitelement 28. The light emitting module 24 comprises a carrier 23 and aplurality of light-emitting devices. The light-emitting device can beany of the light-emitting device 100 (100′ and 100″) mentioned above. Asshown in FIG. 4, for example, twelve light-emitting devices are placedon the carrier 23 comprising six red light light-emitting devices andsix blue light light-emitting devices arranged staggered andelectrically connected to each other (in series or in parallel). Theblue light light-emitting device comprises a phosphor device formedabove to convert the light emitted from the blue light light-emittingdevice. The light emitted by the blue light light-emitting device andthe converted light are mixed to be a white light which is matched witha red light light-emitting device to emit a warm white light having acolor temperature between 2400-3000K.

It will be apparent to those having ordinary skill in the art thatvarious modifications and variations can be made to the devices inaccordance with the present disclosure without departing from the scopeor spirit of the disclosure. In view of the foregoing, it is intendedthat the present disclosure covers modifications and variations of thisdisclosure provided they fall within the scope of the following claimsand their equivalents.

What is claimed is:
 1. A light-emitting device, comprising: a semiconductor stack, comprising a top surface, wherein the top surface comprises a first region and a second region which are coplanar; a current barrier layer formed on the first region, wherein the current barrier layer comprises an insulating material; and a transparent conductive layer formed on the current barrier layer and the second region; and a first electrode formed on the transparent conductive layer; wherein the current barrier layer comprises: an electrode region at a position corresponding to the first electrode, having a shape substantially the same as the first electrode; and a plurality of extension regions extending from the electrode region and not covered by the first electrode.
 2. The light-emitting device of claim 1, wherein the first electrode comprises a first electrode pad and a first extended electrode, and the electrode region of the current barrier layer is under the first electrode pad and the first extended electrode.
 3. The light-emitting device of claim 2, wherein the plurality of extension regions and the first extended electrode extend toward different directions.
 4. The light-emitting device of claim 1, wherein the semiconductor stack comprises four sides and the plurality of extension regions extends toward the four sides.
 5. The light-emitting device of claim 1, wherein the semiconductor stack comprises a first type semiconductor layer, a second semiconductor layer and an active layer therebetween; and wherein the current barrier layer and the first electrode are formed on the second semiconductor layer.
 6. The light-emitting device of claim 5, further comprising: a second electrode formed on and electrically connecting to the first type semiconductor layer; wherein the first electrode comprises a first electrode pad and a first extended electrode; wherein the semiconductor stack comprises a first side, a second side opposite to the first side, a third side and a fourth side opposite to the third side; wherein the first electrode pad and the second electrode are near the first side and the second side, respectively; and wherein part of the plurality of extension regions extends toward the third side and the fourth side.
 7. The light-emitting device of claim 6, wherein one of the plurality of extension regions extends toward the first side.
 8. The light-emitting device of claim 6, wherein the first extended electrode extends toward the second side.
 9. The light-emitting device of claim 6, wherein part of the plurality of extension regions extends from the electrode region which is under the first electrode pad toward at least one of the first side, the second side, the third side and the fourth side.
 10. The light-emitting device of claim 1, wherein the current barrier layer has a sidewall and a bottom surface facing the first region and an angle between the sidewall and the bottom surface is between 10°-70°.
 11. The light-emitting device of claim 10, wherein the transparent conductive layer is formed between the sidewall of the current barrier layer and the second region of the semiconductor stack, wherein a difference between a thickness of the transparent conductive layer at the sidewall on the current barrier layer and a thickness of the transparent conductive layer on the second region of the semiconductor stack forms a ratio not larger than 10%.
 12. The light-emitting device of claim 1, wherein the current barrier layer comprises silicon oxide (SiO₂), silicon nitride (SiN_(x)) or titanium dioxide (TiO₂).
 13. The light-emitting device of claim 1, wherein the current barrier layer has a resistance larger than 10¹⁴ Ω-cm.
 14. The light-emitting device of claim 1, wherein the transparent conductive layer contacts the second region.
 15. The light-emitting device of claim 1, further comprising: a substrate under the semiconductor stack, wherein the substrate comprises an inclined sidewall.
 16. The light-emitting device of claim 15, wherein the inclined sidewall comprises a rough surface.
 17. The light-emitting device of claim 1, wherein in a top view, the electrode region of the current barrier layer has a width larger than that of the first electrode.
 18. The light-emitting device of claim 1, wherein an area of the first region enclosed by a contour of the electrode region of the current barrier layer is larger than an area of the first region covered by the first electrode. 